Bru'n Water Mash pH low

[JDL]

I have used Bru'n water for 5 batches now and the first 3 were spot on but the last two have come in off based on measurement.

First I am using RO water and the TDS is around 5-6 according to the meter while I am filtering it. I also use a Thermoworks 8689 pH meter that I calibrate right before using.

This batch had an estimated pH of 5.37 and came in at 5.01. Which just seems to large to be the pH meter and I am sure I am doing something wrong. I measured out each thing on a calibrated scale or for mL of lactic acid I used a graduated cylinder to make sure I had the right amount.

Appreciate any advice people have to get it dialed back in to where it was the first 3 uses. Of course the beers are different and the grains might be playing a part in it. But all of this has come from the same sack of 2 row as the base of each beer.

I also no sparge so I start off with the complete amount of water needed and treat it all before I start my RIMS.

On the positive side I am sure I will still make beer and it will be tasty from what I can tell when I read about mashing around 5.

 

[mabrungard]

That is odd for Bru'n Water to predict a pH that is higher than observed. Given your TDS reading, it appears your RO unit is working well.

Its good that you're calibrating your pH meter. Are you using reliable 4 and 7 reference solutions? I'm hoping you are cooling your wort samples to room temperature before measuring pH.

Since base malt often dominates the pH of wort, its interesting that you are using the same base malt for all your brews. So a shift in the base malt is not a likely source of the pH difference.

Other than your RO water having high dissolved CO2 (and higher carbonic acid content), I can't imagine how the pH is lower than you intended.

 

[JDL]

The reference solutions were purchased in May of this year and used on each batch as well. Unsure if they are reliable solutions vs unreliable...got them on amazon. https://www.amazon.com/gp/product/B00BUV7L96/?tag=skimlinks_replacement-20

I let the samples sit for a bit and are normally around 70 degrees when I check them.

I saved pics of the grain bags I am currently using, Briess Brewers Malt with a 1.8 Lovibond and its manufacturing date is May of this year kept in a vittle vault.

Some more thoughts I had to help diagnose the problem.

1) Only pulled one sample at 15 minutes into a recirculating RIMS system and maybe I should have pulled another at 30 to tell a difference?

2) I checked the pH of my RO water that I had left over that was not treated after it came in so low 3nd that pH is sitting at 5.14.

4) My last few beers pH at 15-20 Min into mash:

American Wheat - 5.37 (Bru'n Water) - 5.41 (Actual) - 100% RO Water
Oktoberfest - 5.44 (Bru'n Water) - 5.29 (Actual) - Used my own water as it fit the profile better than RO Water
Witbier - 5.35 (Bru'n Water) - 5.21 (Actual) - 100% RO Water

Thanks again for the help.

 

[mabrungard]

Mash pH changes throughout the mash duration. I've found this to be especially true when the pH diverges from about 5.4. In your case, I wouldn't be surprised if the pH rose through the mash and got closer to the 5.4 mark. I also use a RIMS and this variation of pH occurs in my system too.

Don't be too alarmed when early pH readings are not on target. Let the mash progress and recheck the pH. I've found that wort pH tends to naturally trend toward a pH of about 5.4...whether it starts higher or lower than that pH.

 

[JDL]

Thanks, brewing a porter next in a week or so. Will post what happens on that batch as I test it throughout the mash to see if that is the issue.

 

[bluemoon737]

5.14 for your RO water does not sound right. That is very low even for high dissolved CO2.

 

[dammBrewer]

Mash pH changes throughout the mash duration. I've found this to be especially true when the pH diverges from about 5.4. In your case, I wouldn't be surprised if the pH rose through the mash and got closer to the 5.4 mark. I also use a RIMS and this variation of pH occurs in my system too.

Don't be too alarmed when early pH readings are not on target. Let the mash progress and recheck the pH. I've found that wort pH tends to naturally trend toward a pH of about 5.4...whether it starts higher or lower than that pH.

I've noticed similar issues with my last few brews. I also BIAB and without getting into huge details, am curious as well. My Bru n Water calculations for example on my last Imperial Brown Ale were to be 5.6 and taking my measurement at 15 minutes into mash, I got 5.82. I wonder based on your comment Martin, when would you suggest the best time/times to check mash ph? I am open to ideas .

 

[JDL]

Just went and tested some of the RO water I had left over. Tested at 5.85 which maybe would go with the dissolved CO2 theory as it sat out for this long in a little quantity it dissipated on its own? Or maybe a bad reading yesterday on my end?

Another thought I had is I add my water additions the night prior and circulate in the RIMS system for about 20 minutes on full blast to check for leaks, no device hooked up in the mash tun so it just splashes on top of the water. Not sure the effect on water being done so far in advance but the circulation should help dissipate any dissolved CO2?

 

[Big Monk]

What maltster and malt type was it?

 

[bluemoon737]

Just went and tested some of the RO water I had left over. Tested at 5.85 which maybe would go with the dissolved CO2 theory as it sat out for this long in a little quantity it dissipated on its own? Or maybe a bad reading yesterday on my end?

Another thought I had is I add my water additions the night prior and circulate in the RIMS system for about 20 minutes on full blast to check for leaks, no device hooked up in the mash tun so it just splashes on top of the water. Not sure the effect on water being done so far in advance but the circulation should help dissipate any dissolved CO2?

Is this cold water? The colder it is the more readily it is going to absorb CO2 during this "splashing" recirc (and sitting overnight).

 

[bluemoon737]

Also what is your brewing area like? Enclosed area with maybe some CO2 bottles/kegs carbonating, etc.

 

[mabrungard]

CO2 dissolved in the water supply will be preferentially passed through a RO membrane into the product water. It can be supersaturated with CO2 for that reason. In places with that problem, they typically run the RO product water through an air-stripping tower to de-gas the water.

 

[bluemoon737]

CO2 dissolved in the water supply will be preferentially passed through a RO membrane into the product water. It can be supersaturated with CO2 for that reason. In places with that problem, they typically run the RO product water through an air-stripping tower to de-gas the water.

But wouldn't you expect his RO permeate TDS numbers to be higher due to the low pH if in fact the pH number is coming from CO2 saturated supply water?

 

[ajdelange]

I don't think we can blame this one on dissolved CO2. Distilled water exposed to the air should come to about pH 5.65. The acidity of that CO2 is about 0.0017 mEq/L wrt mash pH. Compare to the alkalinity of nominal water with alkalinity of 1 to 2 mEq/L run through an RO unit with 99% rejection leaving .01 - .02 mEq/L. This alone is enough to swamp the CO2 not to mention the alkalinity of a typical base malt WRT mash pH which seems to be something like 15.9 ± 4.2 mEq/L

Now lets suppose through some magic that the CO2 concentration in the permeate is 100 times equilibrium. As soon as the mash water is heated that CO2 is in large measure going to escape. But even supposing it doesn't its acidity WRT mash pH is 0.15 mEq/L. Not, in this case, swamped by the unrejected alkalinity but certainly swamped by base malt alkalinity. Since most mashes have a buffering capacity of about 40 mEq/kg·pH assuming 2 liters/kg we see that, if none of the CO2 escaped, we might expect a mash pH of 0.15/20 = 0.0075 pH.

I'd look for another explanation.

 

[JDL]

Thanks for everyones input..good thing about brewing is it is very forgiving and beer is still made. Answered some of the questions below and will let everyone know how the next brew goes. I think I will use the same system but pull a sample every 15 minutes.

The other thing I did not mention is I let the samples sit in 20ml graduated cylinders until I am on to the boil and then test things. Not sure if this resting period could cause issues as well as for the first 2 brews I took a reading as soon as it was the correct temperature.

What maltster and malt type was it?

Briess Brewers Malt 2-Row

Is this cold water? The colder it is the more readily it is going to absorb CO2 during this "splashing" recirc (and sitting overnight).

It is a private well so about 50-55 degrees in the summer where I am at.

Also what is your brewing area like? Enclosed area with maybe some CO2 bottles/kegs carbonating, etc.

It does have CO2 bottles in the area but all in the keezer. Do not suspect I have a leak as I am surprised the tank has lasted this long on the amount of kegs it has carbonated.

 

[Horseflesh]

When is the best time to check the pH?

What if you do a multi step mash? Last time I brewed I got a screwy pH but just realized a change in protocol... A multi step mash... Acid rest, protein rest, hockkurz mash. By the time I took a pH sample, the grain had been wet for about an hour.

 

[Big Monk]

I wonder if the DI pH of the briess malt was lower than the 5.75 that BW assumes. That would explain discrepancies in estimated versus measured if other variables are accounted for (calibration, temp, etc.)

 

[ajdelange]

I wonder if the DI pH of the briess malt was lower than the 5.75 that BW assumes. That would explain discrepancies in estimated versus measured if other variables are accounted for (calibration, temp, etc.)

Yes, the DI pH of the base malt will have definite effect on the mash pH but a mash pH of 5.01 can't be explained by that. For example, Rahr pale ale malt has a DI mash pH of about 5.67 and buffering of about -53.6 mEq/ph·kg. This would produce a mash pH, with the specified amounts of lactic acid and 60L crystal, of about 5.52 with the base malt having a deficit of 52 mEq balanced by -18.9 mEq from the crystal malt, -25.4 from the lactic acid and about -8 from the calcium.

Crisp Maris Otter has DI pH of 5.69 but its buffering is -46.6 and thus it produces the same predicted mash pH.

On the other hand, Muntons Maris Otter has a DI mash pH of 5.84 with buffering of - 46.1 leading to a predicted mash pH of 5.66.

We can easily ask what DI mash pH would be required of the base malt for a mash pH of 5.01 and the answer is 5.13. This is, of course, a ridiculously low DI pH for a base malt being associated with a caramel or crystal malt of 10 - 15 L.

When lactic acid is used it is not uncommon to see pH as low as 5 or even below that immediately after strike as what one is measuring is the pH of the water which has not had time to penetrate the grains and react with the bases therein. pH should rise fairly rapidly and be well above 5 after 10 minutes or so and then continue to rise more slowly over the next 10 minutes becoming fairly stable after about half an hour.

If one obtains a reading as low as 5 in a grist like the one described after 10 minutes he should definitely suspect the pH meter, rinse the electrode, blot or shake it dry and return it to the 4 buffer in which it should, of course, read 4 with error less than 0.05 pH. If it does not, recalibrate and check the mash again.

1) Only pulled one sample at 15 minutes into a recirculating RIMS system and maybe I should have pulled another at 30 to tell a difference?

You waited long enough that the low pH reading cannot be attributed to unreacted lactic acid.

2) I checked the pH of my RO water that I had left over that was not treated after it came in so low 3nd that pH is sitting at 5.14.

This suggest that the problem was with the calibration or the electrode itself. As noted in my earlier post the pH of DI water exposed to the air should be about 5.65 but we need to note that DI water pH is very hard to measure. If your reading of 5.14 was relatively stable then we can conclude that the un-rejected ions in the RO water were in sufficient concentration to allow a good reading but that your meter's cal was off quite a bit. I would run the stability test from the Sticky on this meter before using it in brewing again. In doing this, of course, you will want to use fresh buffers.

 

[tracer]

Isn't special B a crystal malt?
tracer

 

[ajdelange]

Doesn't matter as there is so little. Were it sauermalz it would only produce about 0.5 mEq acid as compared to 26 mEq from the lactic. The pH shift would shift less than 0.01 pH if this malt were left out.

 

[JDL]

ajdelange,

Thanks for the input. Will try your suggestions and plan on brewing a porter in about a week and will see how it goes.